import math

x1,y1,x2,y2 = map(float, input().split())

# https://en.wikipedia.org/wiki/Euclidean_distance
dx = x1 - x2
dy = y1 - y2
print(math.sqrt(dx ** 2 + dy ** 2)) import math math x1,y1,x2,y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 dx = x1 - x2 dx x1 - x2 x1 x2 dy = y1 - y2 dy y1 - y2 y1 y2 print(math.sqrt(dx ** 2 + dy ** 2)) print math.sqrt(dx ** 2 + dy ** 2) math.sqrt math sqrt dx ** 2 + dy ** 2 dx ** 2 dx 2 dy ** 2 dy 2 x2,y2 = map(float, input().split()) map(float, input().split()) x2 dx = x1 - x2 x1 - x2 dx y1,x2,y2 = map(float, input().split()) map(float, input().split()) y1 y2 = map(float, input().split()) map(float, input().split()) y2 x1,y1,x2,y2 = map(float, input().split()) map(float, input().split()) x1 dy = y1 - y2 y1 - y2 dy
import math

x1,y1,x2,y2 = map(float, input().split())

# https://en.wikipedia.org/wiki/Euclidean_distance
dx = x1 - x2
dy = y1 - y2
print(math.sqrt(dx ** 2 + dy ** 2))
